1. Field of the Invention
The present invention relates to a bump stopper cap which is attached to a shock absorber and collides with a bump stopper when the shock absorber contracts.
2. Description of the Related Art
For instance, a shock absorber comprises a bump stopper which regulates a contraction stroke thereof. For example, the bump stopper is attached to a piston rod in face of a bump stopper cap fixed to the upper end of a cylinder main body (absorber shell) of the shock absorber, as shown in Patent Document 1. The bump stopper collides with the bump stopper cap to regulate the contraction stroke of the shock absorber and absorbs an impact at the time of the collision, when a wheel is thrust up and the shock absorber contracts greatly.
As shown in FIG. 11, for instance, the bump stopper cap 200 is integrally formed in a configuration wherein one end of the circular-cylinder portion 210 formed in a shape of a cylinder is plugged up with a top board portion 220 in a shape of a ring. Recently, many bump stopper caps 200 are integrally formed with a resin material. The bump stopper cap 200 is pressed into and fixed to the tip of the cylinder main body 110 in a status that the piston rod 120 of the shock absorber 100 was inserted into the through-hole 230 drilled in the top board portion 220. The front face 220b of the top board portion 220 serves as a collision surface which collides with the bump stopper 400 (refer to FIG. 12), and the back face 220a of the top board portion 220 serves as a seating surface which is seated on the nib surface 110b of the cylinder main body 100.
The interference portion 300 which squeezes the outer circumference surface 110a of the cylinder main body 110 inward in a radial direction is formed in the inner circumference surface 210a of the circular-cylinder portion 210. The interference portion 300 is formed by integrally forming a rib prolonged along an axial direction on the inner wall of the circular-cylinder portion 210 at a predetermined interval in a circumferential direction, for example. This interference portion 300 is formed to extend to a portion connected with the top board portion 220 in the circular-cylinder portion 210 (referred to as the connecting portion 240), i.e., to the nib of the circular-cylinder portion 210 along the axial direction. In addition, as the interference portion 300, in place of the rib, interference may be formed on the whole circular-cylinder object.